I'm just using the windshield antenna, and I've been perfectly happy with the reception. I suspect you could buy a short extender at radio shack or partsexpress, though, if you want to use the rear antenna.
The extension cables are only a few bucks. For that matter, I probably have a few lying around...let me know what length you need and which type (male, female motorola, etc.) and possibly we can work something out.
Using the windshield antenna works fine too, assuming you live pretty close to your stations. Try that first.